1. Field of the Invention
This invention relates to stabilization of a pharmaceutical composition containing ticlopidine hydrochloride. The stabilization is achieved using stearic acid, which also serves as a lubricant.
2. Prior Art
For ease of administration of a drug, a drug is often made into the form of a tablet or capsule. Invariably, in order to make a drug into a tablet or capsule, it is necessary to use additional ingredients to serve as diluents, binders, disintegrants, lubricants and for other purposes. These additional ingredients are referred to in the pharmaceutical industry as "excipients", and are selected from substances known to be pharmacologically inactive and nontoxic.
The excipients must be selected not only to serve their desired purpose, but also such as to produce a composition that is stable. For some drugs, inclusion of certain excipients in the composition will accelerate the decomposition of the drug, and it is necessary either to exclude such excipients or to add others that will act as stabilizers and prevent the decomposition.
Ticlopidine hydrochloride is an example of a drug known to be susceptible to accelerated decomposition if certain excipients are included.
It is to be apparent to those skilled in the art that there are other such substances with similar properties.
It is to be understood that for the purposes of the specification and claims, the term active ingredient will mean such substances such as ticlopidine hydrochloride which are subject to decomposition in the presence of magnesium stearate and the like.
U.S. Pat. No. 4,591,592 to Syntex teaches that compositions containing the drug ticlopidine hydrochloride have exhibited unacceptably rapid decomposition as a result of the inclusion of certain excipients, such as gelatin, povidone and magnesium stearate. U.S. Pat. No. 4,591,592 further explains that compositions containing the drug ticlopidine hydrochloride can be stabilized by the addition of acidic compounds.
Most pharmaceutical tablets and capsules include magnesium stearate as a lubricant, and, as aforesaid, use of magnesium stearate accelerates the decomposition of ticlopidine hydrochloride.
U.S. Pat. No. 4,591,592 purports to overcome this problem by adding an acidic compound as a stabilizing ingredient. However, the use of an acid as a stablizer in addition to the use of magnesium stearate as the lubricant makes the composition more complex than desirable. Furthermore, although the compositions of U.S. Pat. No. 4,591,592 are more stable than other compositions containing ticlopidine hydrochloride, they are still less stable than desired.
One object of the present invention is to enable production of a pharmaceutical composition containing the drug ticlopidine hydrochloride in which a single substance is used as both lubricant and stablizer.
A second object of the invention is to enable production of a pharmaceutical composition containing the drug ticlopidine hydrochloride which has stability superior to the compositions of U.S Pat. No. 4,591,592.